Pneumatic door-control device



Nov. 29, 1966 B. v. DOMAS ETAL 3,287,758

PNEUMATIC DOOR-CONTROL DEVICE Filed M y 15, 1964 4 Sheets-$heet l I'] ll FIG.

FIG. 2

INVENTORS: BEN V. DOMAS BY GLENN B. MORSE Afiy.

PNEUMATIC DOOR-CONTROL DEVI CE Filed May 15, 1964 4 Sheets-Sheet 53 FIG. 3

BEN V. DOMAS GLENN B. MORSE INVENTORJ FIG. 4

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Nov. 29, 1966 B. v. DOMAS ETAL 3,287,758

PNEUMATIC DOOR-CONTROL DEVICE Filed my 1.5, 1964 4 Sheets-Sheet 5 FIG 6 BE N V. DOMAS GLE NN B. MORSE INVENTORS Nov. 29, 1966 B. v. DOMAS ETAL PNEUMATIC DOOR-CONTROL DEVICE 4 Sheets-Sheet 4 Filed May 15, 1964 I NVEN TOR$ B E N V. DO MAS GLE N N B. M OR 8 E l w w United States Patent 3,287,758 PNEUMATIC DOOR-CONTROL DEVICE Ben V. Dumas, 1450 Buell Road, Rte. 2, Lake Orion, Mich, and Glenn B. Morse, Rte. 3, Grand Rapids, Mich.

Filed May 15, 1964, Ser. No. 367,835 1 Claim. (Cl. 16-84) This invention relates to pneumatic devices used to control the rate of movement of associated equipment, and has been developed primarily to control the closing of the doors of commercial passenger vehicles. Usually, it is desirable that the door open freely to minimize resistance to the actuating mechanism. Closing of the door is then accomplished by release of the forces holding the door open, leaving the closing movement determined by the interaction of a biasing means and a rate-control device. It is the latter that is the subject of this invention.

It is conventional practice to cushion the closing movement with an air cylinder, and to control the rate by regulation of the escape of air from the compression side of the piston either (a) to the atmosphere or (b) to the opposite side of the piston. Control of the pressure conditions on the suction side of the piston is also conventional. A full closure of the door is best obtained by dumping the compressed air ahead of the piston just prior to the end of the stroke. This produces a snap-shut action without slamming, and without endangering the passengers. Much prior development has taken place in this field, and the present invention centers in improvements providing these features at comparatively low cost, and with an adjustability that facilitates the maintenance of performance without disassembly.

The several features of the invention will be analyzed in detail through a discussion of the particular embodiments illustrated in the accompanying drawings. In the drawings:

FIGURE 1 is a sectional elevation of one modification of the invention, in the condition corresponding to the open position of a door.

FIGURE 2 is an end elevation of the device shown in FIGURE 1.

FIGURE 3 is a sectional elevation of the mechanism shown in FIGURE 1, in a condition corresponding to full closure of the door.

FIGURE 4 is a perspective view of the dump valve shown in FIGURES 1 and 3.

FIGURE 5 is a sectional elevation of a modified form of the invention, in the condition corresponding to the open position of a door.

FIGURE 6 is an end elevation of the device shown in FIGURES 5.

FIGURE 7 is a perspective view of the adjustable exhaust valve shown in FIGURE 5.

FIGURE 8 is a perspective view of an adjusting key used in conjunction with the device shown in FIGURE 5.

FIGURE 9 is a sectional elevation of a further modification of the invention, shown in the condition corresponding to the open position of a door.

FIGURE 10 is an end view of the device shown in FIGURE 9.

Referring to FIGURES 1 through 4, the cylinder is provided with the heads 21 and 22 closing the opposite ends, this assembly being secured by the four rods 23-26 extending between the heads 21 and 22, and at the side of the cylinder 20. These rods have threaded ends engaged by standard nuts as shown at 23a-26a. This construction is conventional in this field. The head 22 is provided with a bearing insert 27 for slidably receiving the piston rod 28, and a conventional seal unit 29 is secured to the head 24 by screws 30-33. The

ice

opposite head 21 is frequently provided with a threaded bore 34 as a means of attaching the device to a mounting bracket (not shown). The piston rod 28 may be formed in any convenient manner for coupling to a pivot bracket (not shown) normally mounted on a door or other con trolled device. The illustrated unit has a threaded bore 35 in the outer end of the piston rod, and a portion of reduced diameter indicated at 36 for registry with the receiving fitting. This portion of the device forms no part of the present invention.

The opening of a door is accomplished by actuating mechanism (not shown), and the resulting movement of the door moves the illustrated control device to the position shown in FIGURE 1, with the piston 37 adjacent the head 21. The piston is in threaded engagement with the piston rod 28 as shown at 38, and moves with the piston rod at all times. As the actuating mechanism is released, the closing movement of the door under the forces applied by a biasing system (not shown) has the effect of moving the piston rod 28 and the piston 37 to the left in the cylinder 20, as shown in FIGURE 1. During this movement, the air to the left of the piston becomes compressed, and thus reduces the rate of closure of the door. A vent port may be incorporated in the cylinder as shown at 39, the effect of this being to postpone or reduce the restricting action imparted by the compressed air. After the piston 37 has passed the port 39, however, this port has no substantial effect on controlling the rate of closure until the piston has passed the port, which then releases any vacuum effect behind the piston. A small degree of leakage is usually present around the piston 37, or through the various joints of the device. This condition provides a degree of by-pass which limits a build-up of pressure to the left of the piston and the vacuum to the right of it. The amount of flow through such by-pass conditions, together with the intensity of the biasing action, will control the rate of closure of the door until the piston 37 contacts the end 40 of the dump valve 41. When this condition takes place, the conical surface 42 becomes disengaged from the valve seat 43, and permits flow of air through the bore 44, and past the flat surfaces 45 of the valve 41. The width of the valve 41 across the diagonals at the intersection of the fiat surfaces 45 is slightly less than the diameter of the bore 44, and the valve 41 is freely slidable within this bore against the action of the spring 46. Sliding movement of the valve can continue until the actuator portion 47 has been pushed completely into the head 22, as shown in FIGURE 3. The compressed air to the left of the piston 37, after passing the valve 41, proceeds to the left through the bore 44, through the central opening 48 in the retaining screw 49, and from there out throughthe open end of the threaded portion of the bore 44. It is significant that this valve assembly is mounted within the tubular member 50 which is threaded on its exterior surface, and in engagement with corresponding threads in the head 22. The head 51 on the member 50 makes it possible to rotate the entire valve unit in its threaded engagement with the cylinder head 22, resulting in movement to the left or right, depending upon the direction of rotation that is imparted to it. The effect of this is to alter the point in the stroke of the piston 37 at which the end 40 of the actuator 47 of the dump valve is contacted. The function of the dump valve 41 is supplemented by the opening of the port 39 as the piston 38 passes it. The combined release of pressure and vacuum near the end of the stroke snaps the door to the fully closed position. During the time the piston has covered the port 39, the arresting elfect of the unit is at a maximum, serving to check any objectionable build-up of closing velocity. Opening of the port 39 also tends to prevent snap-back by release of the energy imparted by door inertia.

It is preferable to incorporate a flow-control device 52 of conventional design in a passage 53 formed in the cylinder head 21. The usual arrangement of the flow control device 52 is to provide relatively free passage of air outward, and limit it or prevent it entirely in an inward direction with respect to the cylinder 20. On the closing movement of the door, this flow will contribute to the control of the conditions on the suction side of the piston 37.

Referring to FIGURES through 8, the control device illustrated in these views includes a cylinder 54 to which the heads 55 and 56 are secured with the bolt rods 57-60, as previously described in connection with FIGURE 2. A bearing insert 61 and a seal plate 62 are also incorporated in the head 55. In this modification of the invention, the adjustment of the rate of closure of the door can be accomplished by varying the position of the bypass control valve 63 mounted in the piston 64. The passage 65 communicates between opposite sides of the piston 64, and is provided with a valve seat 66 operating in conjunction with the conical surface 67 on the valve 63. A vent passage 68 along the side of the valve 63 permits flow of air beside the valve, and rotary adjustment of the valve will bring the surface 67 to and from a sealing relationship with the surface 66, producing a throttling action which regulates the flow through the passage 65. The adjustment of the valve 63 is accomplished through the use of the key 69 shown in FIGURE 8. The body 70 of this key is receivable in the bore 71 in the piston 64, and the extension 72 is hexagonal in crosssection to cooperate with the standard driving recess in machine screws. The valve 63 may be easily made from a conventional set screw. Access to the end of the valve 63 is provided through the opening 73 in the head 56, and the distance of the axis of this opening from that of the cylinder 54 is established to beidentioal with that of the passage 65. The piston 64 and the piston rod 74 may be rotated with respect to the cylinder 54 either by the application of a pipe wrench to the exterior portion of the rod 74, or through the insertion of a suitable tool in the diametral hole 75. Such rotation is continued until the key 69 slips into the bore 71, at which time the end 72 can be adjusted to engage with the mating recess in the valve screw 63. When the adjustment has been completed, the cap screw 76 is applied to close off the opening 73. This arrangement provides a controlled by-pass without exterior conduit connections, and without requiring extensive disassembly of the unit in order to efiect the adjustment. A relatively unobstructed movement of the piston to the right (on the opening of the door) is accomplished by incorporating the ball valve 77 in the piston 64, and which functions under the action of the spring 78. A vented retaining screw 79 forms a base against which the spring 78 can act, and the presence of compression to the right of the piston 64 will result in the unseating of the valve 77, and flow of air through the passage occupied by this assembly.

Referring to FIGURES 9 and 10, the control device illustrated in these FIGURES includes the cylinder 80 provided with the head members 81 and 82 secured with the bolt rods 83-86, as previously described. A seal plate 87 is also incorporated. The piston 88 is mounted in threaded engagement at the end of the piston rod 89, and contains a passage 90 which may be considered as a permanent metering passage controlling the rate of bypass with respect to the piston. An auxiliary adjustable vent unit is shown at 91, and the screw 92 is operative to control the exhaust flow out through the passage 93. The installation of this unit at an intermediate point along the cylinder establishes an adjustable exhaust during a predetermined and limited range of the stroke of the piston 88. The flow-control device 94 is normally operative to permit a free outflow of air to the right of the piston 88, and a limited or blocked flow inward. In the latter case, the closure rate of the door is determined by the diameter of the metering passage 90, in conjunction with the adjustment of the intermediate control 91.

The particular embodiments of the present invention which have been illustrated and discussed herein are for illustrative purposes only and are not to' be considered as a limitation upon the scope of the appended claim. In this claim, it is our intent to claim the entire invention disclosed herein, except as we are limited by the prior art.

We claim:

A pneumatic door-control device, comprising:

a cylinder;

a first cylinder head member normally secured to one end of said cylinder, said first head member having a bearing and a bore disposed on an axis parallel to that of said cylinder;

at second cylinder head member normally secured to the opposite end of said cylinder;

a piston slidably mounted in said cylinder;

a piston rod slidably received in said bearing and secured to said piston; and

a dump valve mounted in one of said head members, said valve having an actuator normally extending into said cylinder for engagement with said piston at a position near the end of the stroke thereof, and operative to open an exhaust passage from said cylinder on actuation by said piston, said valve including a tubular housing mounted in threaded engagement with said one cylinder head member for axial adjustment with respect to said cylinder to determine the position of said piston where contact is made with said actuator, and

said valve also including a member slidably mounted in said tubular housing, and having a valve surface engageable with a valve seat in said tubular housing, and further includes biasing means urging said valve to closed position, said biasing means being operative to maintain closure of said valve against normal cylinder pressures, but yieldable against normal piston forces.

References Cited by the Examiner UNITED STATES PATENTS 1,036,340 8/1912 Rockwell et a1.

3,059,269 10/1962 Selinger etal. "16-66 FOREIGN PATENTS 408,565 1934 Great Britain.

758,607 10/1956 Great Britain.

EDWARD C. ALLEN, Primary Examiner.

JOSEPH D. SEERS, Examiner.

P. TEITELBAUM, Assistant Examiner. 

